Microsoft and Yahoo are holding informal merger discussions, marking a shift from the "radio silence" that previously existed between the two companies, according to a source familiar with the talks.

A lot has changed over the past two weeks, compared with February 1 when Microsoft issued its unsolicited buyout bid for Yahoo, which initially valued the company at $31 a share.

"Yahoo has shown some willingness to have a conversation and talk," said the source on Wednesday. The source noted the Redmond giant has since come to the conclusion it may never get a formal rejection letter from Yahoo.

Whether these informal talks will lead to a deal has yet to be seen, added the source.

The recent events add further clarity to comments Microsoft CEO Steve Ballmer made at CeBIT a couple weeks ago, in which he said "'there is a range of dialogue' for both companies about the proposed takeover," as cited in an Associated Press report.

Another source close to Microsoft's Yahoo buyout efforts, however, cautioned Thursday that if the talks had reached a substantive level, Microsoft would have disclosed it publicly.